1778 HUMAN ANATOMY. 



value. The obturator nerve, which is in close relation with the vessel and the track 

 of the hernia, supplies the hip- and knee-joints and the adductor muscles and aids in 

 furnishing sensation to the inner side of the thigh as low as the knee, and sometimes 

 to the middle of the leg. Pain in these joints and in that region not otherwise 

 explicable, and especially if associated with intestinal symptoms, should therefore 

 suggest a careful examination of the obturator region. 



Sciatic herniae include all the hernia; that emerge from the pelvis through one 

 or other of the sciatic foramina, — that is, (i) through the great sacro-sciatic foramen 

 alongside of the gluteal artery (above the pyriformisj ; (2) through the same fora- 

 men alongside of the sciatic nerve and artery (below the pyriformis) ; (3) through 

 the lesser sacro-sciatic foramen (Sultan). They are all very rare. The pelvic 

 fascia forms one of the coverings of the sac. Within the pelvis the hernia is anterior 

 to the pyriformis muscle and sciatic nerve. On entering the thigh the sac crosses 

 over the nerve to its posterior surface, and is covered by the gluteus maximus. As 

 the rupture enlarges, it emerges from beneath the lower border of the gluteus and 

 descends the thigh, or may pass forward above the trochanter towards the groin. 



When the hernia is small and makes no obvious swelling in the buttock, it is 

 found at the spot where the sciatic artery is tied just outside the pelvis. A line is 

 drawn from the posterior superior iliac spine to the trochanter major rotated inward, 

 and about half an inch below the junction of the upper with the middle third of this 

 line the hernia enters the buttock (Macready). 



Perineal herniae include those which pass through the outlet of the pelvis and 

 its muscular floor. The boundaries of the former are the glutei maximi and coccyx 

 posteriorly, the pubo-ischiatic arch anteriorly, and the great sacro-sciatic ligaments con- 

 necting the coccyx and the tuberosities of the ischium (Fig. 1423). The coccygeus 

 and levator ani muscles form the floor of this space, which is perforated by the rectum 

 and urethra and vagina, and extends from the outer walls of these structures to the 

 inner walls of the pelvis (Fig. 1424). It might be supposed that the comparatively 

 yielding nature of the parts which close the lower opening of the pelvis would 

 favor the production of herniae, but, as Macready has shown, hernia through muscular 

 planes is everywhere very infrequent. The normal oblique inclination of the pelvic floor 

 and its elasticity are doubtless factors in preventing the occurrence of perineal 

 herniae. A hernia starting at the upper surface of the pelvic diaphragm must pass 

 between the coccygeus and levator ani or between the fibres of the latter muscle, and 

 will descend into the ischio-rectal space (Fig. 1423 ), where it may cause a protrusion 

 of the skin of the perineum, or may advance towards the rectum {rectal hernia), 

 the vagina {vaginal heryiia^, or the posterior portion of the labium majus {ptidendal 

 hernia). 



The development of perineal hernia is believed by Ebner to depend upon an 

 abnormally low descent of the recto-uterine peritoneal fold which occupies Douglas's 

 pouch in the female or of the recto-vesical fold in the male. In the presence of such 

 a fold, intra-abdominal pressure is able to carry a peritoneal pouch, with or without 

 included intestinal coils, to the right or left (its progress in the mid-line being 

 arrested by the firm septum between the rectum and vagina or the rectum and 

 urethra), so that it rests on the levator ani muscle, the fibres of which are often 

 separated at places (Henle describes it as three muscles). Its subsequent downward 

 progress has been noted {vide stipra). 



A form of perineal hernia known as itignino-perineal has been described (Coley) 

 in which the hernial sac accompanied — or followed — the misplaced testicle (ectopia 

 perinjealis ) into the perineum. 



Diaphragmatic herniae are usually congenital and due to defective develop- 

 ment of the diaphragm. A review of the anatomy of that muscle, with special refer- 

 ence to its various openings and to the fissures between its sternal and costal and 

 costal and lumbar portions (Fig. 549), will explain the occurrence of hernial orifices 

 in certain situations, already detailed in connection with hernia of the stomach 

 (page 1632). 



The symptoms gre largely those due to gastric disturbance (when the stomach 

 is involved) and to alteration in physical signs caused by compression and displace- 

 ment of the heart and lungs. 



